Tyrer-Cuzick alternative: IBIS breast cancer risk model options and how they compare

Short version. Tyrer-Cuzick (IBIS) estimates an individual's lifetime and 10-year breast cancer risk, integrating family history with hormonal and reproductive factors, benign breast disease, and optionally mammographic density. Its strength is lifetime risk for screening-intensity and chemoprevention decisions. BRCAPRO estimates BRCA1 and BRCA2 carrier probability directly, using family history, and is stronger for testing-eligibility decisions. The two tools answer different clinical questions and are often used together. Evagene integrates BRCAPRO on the pedigree canvas; it does not currently implement Tyrer-Cuzick. Services that need both run both, with Evagene as the pedigree management layer that can feed family-history data to external Tyrer-Cuzick tools such as IBIS.

What Tyrer-Cuzick is

The Tyrer-Cuzick model — published by Jack Cuzick and Stephen Tyrer and developed through the IBIS (International Breast Cancer Intervention Study) — was designed to estimate an individual's breast cancer risk over defined time horizons, typically lifetime (to age 85) and 10 years. It was deliberately built to be broader than family-history-only models, because many women at clinically significant risk do not have a dramatic family history but do have combinations of hormonal, reproductive, and density factors that shift their lifetime risk meaningfully.

Delivered through the IBIS Risk Evaluation Tool, Tyrer-Cuzick has become one of the most widely used lifetime risk calculators in breast cancer clinical practice, particularly in the UK where it is referenced within the NICE familial breast cancer guideline (CG164) for determining enhanced surveillance eligibility and is used in chemoprevention discussions. Recent revisions of the model include an optional mammographic density input, further improving calibration in women with dense breasts.

What Tyrer-Cuzick takes as input

Tyrer-Cuzick's inputs fall into four categories.

• Personal history. Age, height, weight (for body mass index), ethnicity, and personal history of atypical hyperplasia, lobular carcinoma in situ, or other proliferative benign breast disease.
• Hormonal and reproductive factors. Age at menarche, parity and age at first live birth, menopause status and age at menopause, past and current use of hormone replacement therapy, and past oral contraceptive use.
• Family history. First-degree and second-degree relatives with breast and ovarian cancer, with ages of diagnosis, bilateral disease, and male breast cancer. Ashkenazi Jewish heritage is captured for population-specific effects. Deeper pedigree information (third-degree relatives, cancers beyond breast and ovarian) is handled less granularly than in BRCAPRO or BOADICEA.
• Mammographic density. Optionally, BI-RADS density category or a quantitative density percentage, which meaningfully shifts risk in either direction.

The output is a point estimate of 10-year and lifetime breast cancer risk, with thresholds for standard, moderate, and high risk that correspond to screening-pathway categories in guidelines such as NICE CG164. A lifetime risk of 30 percent or more, for example, is the common threshold for the high-risk category that unlocks enhanced screening with MRI.

Tyrer-Cuzick vs BRCAPRO: different questions

The most common confusion about Tyrer-Cuzick and BRCAPRO is assuming they compete. They do not. They answer different clinical questions, and a well-run breast cancer genetics service uses both.

BRCAPRO's primary output is the posterior probability of carrying a pathogenic variant in BRCA1 or BRCA2, given the family history. Cancer risk projections are derived from that probability via the penetrance functions. BRCAPRO is therefore the stronger tool when the clinical question is: "Should we offer this patient BRCA genetic testing?" The probability threshold for offering testing is the primary decision, and BRCAPRO is built around that probability.

Tyrer-Cuzick's primary output is the projected breast cancer risk over a defined time horizon, integrating genetic, hormonal, reproductive, and density factors. Tyrer-Cuzick is therefore the stronger tool when the clinical question is: "What screening intensity should we offer this patient, and is chemoprevention warranted?" The absolute lifetime risk is the primary decision, and Tyrer-Cuzick's integration of non-genetic risk factors is central to getting it right.

In services that handle both testing-eligibility and screening-intensity decisions — which is most hereditary breast cancer services — both tools are used, often in the same patient session.

When clinicians use which

A simplified decision scaffold — and one no substitute for individual clinical judgement — looks like this.

• Family history consistent with a BRCA1/BRCA2 pattern (early-onset, bilateral, ovarian, male breast, Ashkenazi Jewish heritage). Run BRCAPRO to estimate carrier probability and triage for testing. Consider BOADICEA for the comprehensive picture if testing proceeds or if moderate-penetrance gene coverage matters.
• Family history less clear-cut; question is whether enhanced screening is warranted. Run Tyrer-Cuzick for lifetime risk. If the lifetime risk is high enough to trigger enhanced surveillance under local guidelines, that is the primary decision.
• Combination — family history suggestive but not dramatic, plus hormonal/reproductive or density factors that might shift risk. Run both BRCAPRO (or BOADICEA) and Tyrer-Cuzick. Use BRCAPRO for testing decisions and Tyrer-Cuzick for screening intensity.
• Chemoprevention discussion (tamoxifen, anastrozole) for a woman at elevated but uncertain risk. Tyrer-Cuzick lifetime risk is the usual quantitative basis, because chemoprevention efficacy data is framed around absolute risk.

Why someone might look for a Tyrer-Cuzick alternative

The phrase "Tyrer-Cuzick alternative" typically covers a few underlying needs.

• Integrated pedigree management. IBIS is a lifetime risk tool, not a pedigree management platform. Services that want the pedigree to live inside a clinical genetics platform — with disease annotation, risk models, and AI interpretation — are looking at a different category of product.
• Different clinical question. If the primary question is really about BRCA carrier probability or multi-gene testing eligibility, BRCAPRO or BOADICEA is a better fit than Tyrer-Cuzick.
• Programmatic access. Services building pipelines, EHR integrations, or AI agents that need to run risk calculations programmatically want an API. IBIS does not primarily target this.
• AI-assisted interpretation. Drafting structured narrative reports that combine pedigree findings with risk results is increasingly part of the workflow. This is adjacent to Tyrer-Cuzick's scope rather than a replacement for it.

In most of these cases, the practical answer is not "replace Tyrer-Cuzick" but "add a complementary tool for the piece of the workflow Tyrer-Cuzick does not cover."

How Evagene complements Tyrer-Cuzick

Evagene is not a Tyrer-Cuzick implementation. It integrates BRCAPRO, MMRpro, and PancPRO from the BayesMendel suite directly on the pedigree canvas, along with Mendelian inheritance models for autosomal dominant, autosomal recessive, and X-linked conditions. For the carrier-probability side of the hereditary breast cancer workflow, Evagene is a complete answer. For the lifetime risk side — the Tyrer-Cuzick side — Evagene does not replace the tool.

Where Evagene helps, for services that also use Tyrer-Cuzick, is in pedigree management and data exchange. The pedigree is the shared source of family-history information for both BRCAPRO and Tyrer-Cuzick. In Evagene, the pedigree is drawn or imported once — from GEDCOM 5.5.1, JSON, 23andMe, image OCR — and BRCAPRO runs on it directly. For the Tyrer-Cuzick step, the same pedigree can be exported or referenced, and the non-genetic Tyrer-Cuzick inputs (hormonal, reproductive, benign breast disease, density) are entered in the IBIS interface. The pedigree does not need to be reconstructed.

Three Evagene-specific capabilities are worth noting for services that use Tyrer-Cuzick. AI interpretation with bring-your-own-key LLMs can combine BRCAPRO results with externally-generated Tyrer-Cuzick figures into a single drafted clinical summary, which the clinician reviews. Batch risk screening runs BRCAPRO, MMRpro, PancPRO, and Mendelian analyses across the full 200-plus disease catalogue in a single operation, catching non-breast signals that might be missed if only a breast-specific model were run. And the REST API and MCP server make pedigree and risk data programmatically available, supporting pipelines that also call Tyrer-Cuzick externally. Docs are at evagene.net/help. Evagene is free during Alpha via the waiting list.

Frequently asked questions

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